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serial: 8250_exar: Clear buffer before shutdown 

When closing and shutting down the exar serial port, if the chip
has not finished sending all of the data in its buffer, the
remaining bytes will be lost.  Hold off on the shutdown until the
bytes have all been sent.

Signed-off-by: Robert Middleton <robert.middleton@rm5248.com>
Link: https://lore.kernel.org/r/20190801145640.26080-1-robert.middleton@rm5248.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Robert Middleton 2019-08-01 10:56:40 -04:00 committed by Greg Kroah-Hartman
parent b2b4b8ed3c
commit 47b1747f70
1 changed files with 23 additions and 0 deletions
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23
drivers/tty/serial/8250/8250_exar.c
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@ -19,6 +19,7 @@
#include <linux/string.h>
#include <linux/tty.h>
#include <linux/8250_pci.h>
#include <linux/delay.h>
#include <asm/byteorder.h>
@ -515,6 +516,27 @@ static irqreturn_t exar_misc_handler(int irq, void *data)
return IRQ_HANDLED;
}
static void
exar_shutdown(struct uart_port *port)
{
unsigned char lsr;
bool tx_complete = 0;
struct uart_8250_port *up = up_to_u8250p(port);
struct circ_buf *xmit = &port->state->xmit;
int i = 0;
do {
lsr = serial_in(up, UART_LSR);
if (lsr & (UART_LSR_TEMT | UART_LSR_THRE))
tx_complete = 1;
else
tx_complete = 0;
msleep(1);
} while (!uart_circ_empty(xmit) && !tx_complete && i++ < 1000);
serial8250_do_shutdown(port);
}
static int
exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
{
@ -555,6 +577,7 @@ exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
uart.port.flags = UPF_SHARE_IRQ | UPF_EXAR_EFR | UPF_FIXED_TYPE | UPF_FIXED_PORT;
uart.port.irq = pci_irq_vector(pcidev, 0);
uart.port.dev = &pcidev->dev;
uart.port.shutdown = exar_shutdown;
rc = devm_request_irq(&pcidev->dev, uart.port.irq, exar_misc_handler,
IRQF_SHARED, "exar_uart", priv);